The present invention relates to a cutting head for a cutting tool and, more particularly, to a replaceable cutting head.
It is often useful to provide replaceable cutting heads on toolholders to permit replacing small, relatively quickly worn parts of a cutting tool without also requiring replacement of larger shank structures. One solution for attaching a replaceable cutting head to a toolholder is provided by the PRECIMASTER head reamer tool available from Seco Tools AB, Fagersta, Sweden. The attachment arrangement provided by the PRECIMASTER tool provides a number of strengths, such as run out precision, ease of use, and permitting sending coolant or flushing liquid through the tool. However, transmission of torque between the shank and the cutting head is done via a pin that extends through the shank and the cutting head. It is also difficult to form the entire cutting head in a monobloc construction because of complex shapes used for connection of the cutting head to the shank. This drawback has made it necessary to braze cutting inserts onto a steel body, which has made it impossible to provide larger numbers of teeth or cutting edges on smaller diameter cutting heads. For example, it is not possible to have six teeth on cutting heads with 10 mm or 12 mm diameters. Certain cutting head designs, such as in EP0181093A1, present difficulties because they require complex arrangements for torque transmission that present difficulties with respect to size or strength of the toolholders that would receive them.
It is desirable to provide a cutting head and a cutting tool that can be made in a monobloc construction in very small diameters while permitting provision of large numbers of teeth. It is also desirable to provide a cutting head and cutting tool that provide a simple torque transmission arrangement.
According to an aspect of the present invention, a cutting head for a cutting tool comprises a cutting portion and a shank portion. The cutting portion comprises a plurality of integrally formed cutting edges, and the shank portion has a first end adjacent the cutting portion and a second end. The shank portion has a first portion of the shank portion having a first diameter, a second portion of the shank portion having a second diameter smaller than the first diameter, and a cylindrical third portion of the shank portion having a third diameter larger than the second diameter, the first portion of the shank portion being closer to the first end of the shank portion than the second and third portions of the shank portion and the third portion of the shank portion being disposed closer to the second end of the shank portion than the first and second portions of the shank portion, the first portion of the shank portion having an exterior surface comprising at least one axially extending recess extending from an end of the first portion of the shank portion closest to the second portion of the shank portion toward the first end of the shank portion.
According to another aspect of the present invention, a cutting tool comprises a cutting head comprising a cutting portion and a shank portion, the shank portion having a first end adjacent the cutting portion and a second end, the cutting portion and the shank portion being integrally formed of a uniform material, the cutting portion comprising a plurality of integrally formed cutting edges, and the shank portion having a first portion of the shank portion having a first end and a second end, the first end of the first portion of the shank portion being closer to the cutting portion than the second end, the first portion of the shank portion having a first diameter, and a toolholder comprising a body comprising a first end and a second end, and an axial opening extending from the first end toward the second end, the axial opening comprising a first portion having a first diameter at least as large as the first diameter of the first portion of the shank portion. The first portion of the shank portion has an exterior surface comprising at least one axially extending recess extending from an end of the first portion of the shank portion furthest from the cutting portion toward the first end of the shank portion of the shank portion, the first portion of the axial opening has an interior surface comprising at least one axially extending recess, and at least one ball or axially extending pin is disposed in the at least one axially extending recess of the exterior surface of the first portion of the shank portion and the at least one axially extending recess of the interior surface of the first portion of the axial opening so that the cutting head is non-rotatable relative to the toolholder.